Teleport 16: Advancing Infrastructure Defense in Depth with Device Trust, MFA, and VNET
Jul 25
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Teleport

Machine ID with tctl

tctl is the Teleport cluster management CLI tool. Whilst it usually uses the credentials from the locally logged in user, it is also possible to use Machine ID credentials. This allows tctl to be leveraged as part of a custom automation workflow deployed in a non-interactive environment (e.g CI/CD).

In this guide, you will configure tbot to produce credentials for tctl, and then use tctl to deploy Teleport roles defined in files.

Prerequisites

  • A running Teleport cluster version 16.1.0 or above. If you want to get started with Teleport, sign up for a free trial or set up a demo environment.

  • The tctl admin tool and tsh client tool.

    Visit Installation for instructions on downloading tctl and tsh.

  • To check that you can connect to your Teleport cluster, sign in with tsh login, then verify that you can run tctl commands using your current credentials. tctl is supported on macOS and Linux machines. For example:
    tsh login --proxy=teleport.example.com --user=[email protected]
    tctl status

    Cluster teleport.example.com

    Version 16.1.0

    CA pin sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678

    If you can connect to the cluster and run the tctl status command, you can use your current credentials to run subsequent tctl commands from your workstation. If you host your own Teleport cluster, you can also run tctl commands on the computer that hosts the Teleport Auth Service for full permissions.
  • tbot must already be installed and configured on the machine that will use tctl. For more information, see the deployment guides.

Step 1/3. Configure RBAC

First, Teleport must be configured to allow the credentials produced by tbot to modify the Teleport configuration. This is done by creating a role that grants the necessary permissions and then assigning this role to a Bot.

It's important to grant as few privileges as possible in order to limit the blast radius of an attack, so in this example we grant only the ability to create and update roles.

Create a file called role.yaml with the following content:

kind: role
version: v6
metadata:
  name: example-role
spec:
  allow:
    rules:
    - resources:
      # Specify the names of resources you wish to manage with tctl.
      # For this guide, we will only manage roles.
      - role
      verbs:
      - create
      - read
      - update
      - delete
      - list

Replace example-role with a descriptive name related to your use case.

Use tctl create -f ./role.yaml to create the role.

Now, use tctl bots update to add the role to the Bot. Replace example with the name of the Bot you created in the deployment guide and example-role with the name of the role you just created:

$ tctl bots update example --add-roles example-role

Step 2/3. Configure tbot output

Now, tbot needs to be configured with an output that will produce the credentials needed by tctl. As tctl will be accessing the Teleport API, the correct output type to use is identity.

For this guide, the directory destination will be used. This will write these credentials to a specified directory on disk. Ensure that this directory can be written to by the Linux user that tbot runs as, and that it can be read by the Linux user that tctl will run as.

Modify your tbot configuration to add an identity output:

outputs:
- type: identity
  destination:
    type: directory
    # For this guide, /opt/machine-id is used as the destination directory.
    # You may wish to customize this. Multiple outputs cannot share the same
    # destination.
    path: /opt/machine-id

If operating tbot as a background service, restart it. If running tbot in one-shot mode, it must be executed before you attempt to execute the Terraform plan later.

You should now see an identity file under /opt/machine-id. This contains the private key and signed certificates needed by tctl to authenticate with the Teleport Auth Server.

Step 3/3. Use tctl with the identity output

As an example, tctl will be used to apply a directory of YAML files that define Teleport roles. If these were stored in version control (e.g., git) and this were executed on change, this would form the basis for managing Teleport roles in a GitOps style.

The example role will not be useful within the context of your Teleport cluster and should be modified once you have completed this guide.

Create a directory called roles/ and within it create example.yaml:

kind: role
version: v6
metadata:
  name: tctl-test
spec:
  # This role does nothing as it is an example role.
  allow: {}

To configure tctl to use the identity file, the -i flag is used. As the identity file does not specify the address of Teleport, --auth-server must also be specified with the address of your Teleport Proxy or Teleport Auth Server.

Run tctl, replacing example.teleport.sh:443 with the address of your Teleport Proxy or Auth Server and /opt/machine-id/identity with the path to the generated identity file if you have modified this:

tctl --auth-server example.teleport.sh:443 -i /opt/machine-id/identity create -f roles/*.yaml

Check your Teleport cluster, ensuring the role has been created.

tctl get role/tctl-test

Next steps